The subject matter of the present invention is phenolic resin foams of high filler content, and their use as insulation.
It is known to admix fillers with certain phenolic resol resins so that, when these mixtures are foamed, rigid foams with a high content of fillers are obtained. It is furthermore known that these foams can be of Fire Class A2 and are suitable for use in the building industry for the production of foam insulation materials.
The production of these known hard foams, however, runs into difficulties because the liquid phenolic resol resin which they require is very difficult to foam even at a filler content amounting to 250% of the weight of the liquid phenolic resol resin, and repeatable results cannot be achieved.
It is furthermore disadvantageous in these known rigid foams that they do not have sufficient compressive strength, so that their use in the building industry is problematical. Furthermore, these foams have a shrinkage of about 1% which negatively affects their use in insulation.
The problem therefore was to find some thermosetting rigid foams having a filler content in excess of 100% of the weight of the resin content of the foam, which would still be fluid in the form of foamable mixtures so that they can be foamed easily. Furthermore, the desired foams were to have densities between 200 and 500 kg/cu m, have very little shrinkage, and have a greater compressive strength than known thermosetting rigid foams.